Manufacture of azo dyestuffs



Patented Feb. 16, 1926.

PATENT OFFICE.

rmrz ofinrimn, on nunwmsimrnn-on-mnn-nnmn, GERMANY, Assmnon TO BADISCHEANILIN- 85 SODA-FABRIK,

OF LUDWIGSHAFEN-ONTHE-RHINE, GER- MANY, A conronarron on ennMAnYr-uanuracrunn or azo :ovns'rurrs;

No Drawing.

To all whom it may concern:

Be it known that I, FRITZ GI lNTHER, citizen of the German Empire,residing at Ludwigshafen-on-the-Rhine, Germany, have invented new anduseful Improvements in the Manufacture of Azo Dyestuffs, of which.

the following is a specification.

I have found that azo-dyestuffs of the type salicylic acid-N:N-(P)-ryl-X aryl (p)N=N-salicylio acid containing one or more than onesulfonic acid group and as a linking X either an azo or azoxy group orthe urea grouping excel by very good tinctorial properties, especiallyby dyeing both animal and vegetable fibres fast shades. They are alsovery suitable for dyeing mixed fabrics. In all cases, in the aboveformula, salicylic acid is meant 'to include. also-homologues, such ascresotinic acids and others.

Dyestuffs of the aforesaid type, so far as they contain the azo or theazoxygroupas a linking X, can be obtained from'the azo dyestuffs derivedfrom diazotizcd p-nitroaryl-amine-sulfonic acids and salicylic acid 1 byreducing with the aid of an alkaline re ducing agent 1n such a mannerthat two molecules of the azo dyestuif are linked together by means ofthe nitrogen atoms of the nitro groups. Prob-ably a new azo or an azoxygroup will thereby be formed and act as the linking. The new dyestuffs,contrary to the sulfonated products employed for reduction, have thecharacter of direct dyestuffs and produce from orange to red dish brownshades possessing valuable properties.

The same. or very similar azodyestufl's can also be obtained by startingfrom unsulfonated azo dyestuffs derived from p-nitro-arylamine andsalicylic acid and either -sulfonating it before applying alkalinereduction'or first reducing it by an alkaline ooon' Application a a 'ml1:, i925. Serial m. 43,410.

reducing agent in order to effect the aforementioned linking of twomolecules and sulfonating the reduction product.-

Azo coloring matters in accordance with the type mentioned above, so faras they contain the urea grouping, can be obtained for example, bysulfonating the unsulfonat ed dyestuffs derived from diamino-di-arylureaand two molecules of salicylic acid, or its homologues or derivatives,which sulfonation can be carried out in the usual way without anydecomposition taking place. Very similar sulfonated products can beobtained by diazotizing a sulfonated diamino-diaryl-urea and combiningwith two molecules of the salicylic acid body, or by starting from anamino-arylene-sulfonic acid-azo-sailicylic acid body (for exampleobtained from .p-nitraniline-sulfonic acid and salicylic acid withsubsequent reduction) and treating it with phosgene. The shades producedwith such products are a bright yellow.

The following examples will serve to explain the invention further butthe-invention is not restricted to these examples. The

parts are by weight, unless. otherwise stated.

Ewample 1.

dyestuff eventually filtered off, after adding,

if required, a. little common salt solution. Its structural formula isprobably the following one: a

in which formula Az stands for the azoxy or azo (N=N) group, it beingnot definitely ascertained which one has been formed. It can be furtherpurified by again dissolving it in water and re-precipitating it bymeans of sodium chlorid. When boiled with solutions of suitable chromiumsalts it gives a water-soluble chromium compound which like the dyestuftitself has the roperty of dyeing cotton directly. The yelngs obtainedwith such chromium compound or with a dyeing li uor containing thechromefree d estuif an a suitable chromium salt are 0 an extraordinaryfastness. They have a valuable copper shade.

Ewwmple 2.

The azo dyestuff obtained from para-nitraniline and salicylic acid isreduced in an alkaline bath. to convert the nitro groups into the azo orazoxy group and 20 parts of the reduced and dried dyestuflt' whichprobably has the structural formula:

in which formulas AZ stands for the azoxy or azo (s-N=N-) group, itbeing not defi nitely ascertained which one has been formed, aresulfonated by means of 200 parts of fuming sulfuric acid of 23 percentSO at OOOH about 100 degrees centigrade After sulfonating the mass ispoured into water, heated, preferably with an addition of common salt,filtered and the dyestuff converted into its sodium salt, which can bepurified, if desired, by dissolving in water and reprecipitating withsalt. The dyestuif which prolbably has the following structural formu aOOOH'I dyes animal as well as vegetable fibre brownish red shades.

"Emample 3.

200 parts of the azo-dyestufi from p-nitraniline and salicylic acid areintroduced into between 8 and 10 times their weight of fuming sulfuricacid of 23 percent S0 while stirring and then heating the mixture toabout 100 degrees centigrade for several hours. When sulfonation iscomplete, the

OOOH

OOOH

COOH

dyes ve orange s ades.

E trample 4.

.at room temperature, while stirring, into [HOG etable and fibresbrownish 100 parts of fuming sulfuric acid of 23 per cent S0 andsubsequently heated to about 75 centigrade for a couple of hours.Thereafter, the mass is poured on ice, the 'dyestuff filtered off,washed with water and dissolved in sodium carbonate solution, saltedout, filtered and dried. The structural formula is probably as follows:

' be carried out in an analogous or any usual or suitable way.

Now whatI claim is:

1. As new articles of manufacture azo coloring matters for animal,vegetable and mixed fabrics, which contain the grouping -N- N-ary1 (p)-X (p) ary1N=N-' (X standing for the azo or azoxy group or the ureagrouping), coupled with an orthooxy-carboxylic acid, and containingsulfonic acid groups. I

2. As a new article of manufacture, an

azo dyestufi containing the grouping sal- 3. A process of manufacturingan azo dye stufi, which consists in subjecting azodyestufis derived fromsulfonated paramitxo arylamines and a salic lic acid body to alkalinereduction suitab e to convert two nitro groups into an azo-or =a.zoxygroup.

In testimony whereof I have hereunto set my hand.

FRITZ GUNTHER.

